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Guest opinion: The truth about carbon dioxide, climate and the weather

By Kevin E. Trenberth

Posted:
01/12/2010 01:00:00 AM MST

Two Sundays in a row ill-informed columns about carbon dioxide and climate have appeared in the Camera. The first by Bob Greenlee (Jan. 3) and the second by Charlie Danaher (Jan. 10). Both misrepresent me and my work, and in particular, quote from one of my e-mails that was illegally stolen: "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't."

The quote has been taken out of context. It relates to our ability to track energy flow through the climate system. We can do this very well from 1992 to 2003, when large warming occurred, but not from 2004 to 2008. The quote refers to our observation system which is inadequate to observe Earth's energy flows at the accuracy needed to understand small fluctuations in climate; it does not mean there is no global warming, as is often interpreted by the likes of Danaher. What is does mean is that our observing system is not adequate to fully track the energy in ways that allow us to understand and make best statements about the effects of natural climate variability: the La Niña of 2007-2008, and the current El Niño, for instance.

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It is absolutely certain that carbon dioxide is a greenhouse gas and produces warming, despite Danaher's wishes. Without carbon dioxide and other greenhouse gases, Earth's surface would be some 32 degrees Fahrenheit colder than it is now. Increased carbon dioxide will increase this warming effect, and both theory and observations are consistent with this fact. The evidence of this happening is widespread and abundant, so that the Intergovernmental Panel on Climate Change (IPCC) in 2007 was able to state with unanimous agreement from all of over 100 countries that global warming is unequivocal. But global warming does not stop weather from happening, and cold outbreaks continue and are fully expected. It does not stop winter. And it does not stop La Niña from happening and setting up unusually cold regional patterns of weather across the United States and other parts of the world that last a year or two.

To misunderstand the role of weather and natural climate variability the way it is being done is to undermine much-needed actions in limiting carbon dioxide emissions. Global warming is happening. It will continue to happen and the way we are going it will jeopardize the very nature of climate on planet Earth some decades from now. Because of the long lifetime of carbon dioxide, by the time it is so obvious to everyone, it will be far too late to do anything about it.

Americans should be outraged that the Chinese are putting huge amounts of carbon dioxide into the atmosphere, and changing our climate! But by the same token, the Chinese should be outraged that the United States is putting nearly as much into the atmosphere, and historically a whole lot more than any other country, and changing their climate. We try to outdo each other in mutual self-destruction!

Putting a price on carbon dioxide emissions is an essential first step to responsible management of our planet. The United States needs to show leadership on this critical environmental issue.

Kevin Trenberth is the Head of the Climate Analysis Section at NCAR, and has been a leader in the IPCC, which received the Nobel Peace Prize for its work in 2007. See cgd.ucar.edu/cas/trenbert.html. E-mail: trenbert@ucar.edu.

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